Tradies are being warned to secure building sites as thousands of dollars worth of tools, building materials and even garage doors, insulation and wiring are lost to light-fingered crooks.
The bosses of two major building contractors told the Herald on Sunday on-site thefts had increased in Auckland in the past year, something they put down to the city's housing boom.
Complete Builders' director Amon Johnson said small power tools such as nail guns, drills and sabre saws were most commonly targeted.
But a newly-installed garage door had also been pinched from a property, along with the mobile scaffolding stored inside.
He had also heard of bales of Pink Batts, household appliances, and yet-to-be-laid carpet being taken.
In one case installed wiring was ripped out and stolen, which he estimated cost about $10,000.
"There's been a definite increase in the past six to 12 months, but more so in the past few months," he said.
"Obviously people are doing this as a job. It's good money if you know what you're doing and [what's being taken] makes me think they are stealing to order.
"If it's not bolted down people will steal it."
The increase was a consequence of the city's construction boom, and the situation was particularly bad at Hobsonville Pt, a big residential development.
His company was fastidious about recording serial numbers on tools, so they could potentially be identified as stolen goods, Johnson said.
Costs involved with the thefts, including increased insurance premiums, were eventually passed on to customers.
Harford Construction director Jason Harford had noticed an increase in thefts since Christmas and predicted it would continue for another decade.
"There's so much going on in Auckland city," he said. "We are working in big housing divisions. There are multiple contractors coming through."
Some contractors had a van's worth of gear stolen from outside a house they were working on.
He had once arrived at a site to discover $600 worth of timber missing.
Smaller items such as drills and battery chargers vanished more frequently. "It's those little things that people can walk past and pick up."
Those who were insured were hit with higher premiums because of the the thefts.
Others couldn't afford the high premiums for their tools, Harford said.
However, he was not aware of his company passing on costs to clients.
Auckland police spokeswoman Noreen Hegarty said crime prevention advice and material had been distributed to builders, construction site managers and sub-contractors over the last year "in light of documented increased incidents of reported thefts".